Iron oxide is often used with other components to make black Complex Inorganic Color Pigments (CICP). A CICP is a pigment made by heating a number of different metal oxides. Relatively large, coarse, and/or hard particles often lead to problems in some CICP applications.
The large, coarse, and/or hard CICP particles may be employed in substances such as concrete. However, CICP particles used for coloring coatings, plastics, lacquers and synthetic resins are typically subjected to intensive grinding. The disadvantages associated with intensive grinding include the undesirable formation dust, difficulties in measuring the ground CICP particles, and difficulties in dispensing with the ground CICP particles.
Moreover, in order for CICP particles used for coloring coatings, plastics, lacquers and synthetic resins, high temperature stability is required since these materials are often processed or exposed to high temperatures. As a result, black pigments based upon Fe.sub.3 O.sub.4 cannot be used for coloring coatings, plastics, lacquers and synthetic resins. This is because Fe.sub.3 O.sub.4 is oxidized to brown or red Fe.sub.2 O.sub.3 at high temperatures, such as above 180.degree. C.
Most black CICP formulations have one or two desirable properties as well as several undesirable properties. For example, some black pigments are strong, but have poor weathering characteristics, poor heat resistance, undesirable brown, red and/or yellow shades, and/or costly starting materials. Specifically, PBK 30 is strongly black, but is expensive since it contains nickel. PBK 30 also has improvable weathering characteristics.
Given these circumstances, when employing a black CICP formulation, one must accept a compromise on at least one desirable property. There is thus an unmet need in the art for a black CICP formulation having many desirable properties.